SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fbfb5d4d07af5804dbfbf37e97b3ecfe67074aba62113831088082bd09cd8503' 
  AND token = 'r/ACw2zieBL67sSGWJGwVRjxt5DnYmB+Z8JUdSYfbWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}